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  1. #1
    RC Racer
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    Dec 2004
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    What causes Detonation??

    I am unsure of what causes it......other than hearing the "tiny" explosions when comming off the throttle. are there any other signs?
    Tec Pro 3.3, MIP Stinger,Jaco Nitro Shoes, HPI WRX, VARAD Lighting System...... Check up cause I Will bump draft.

  2. #2
    RC Turnbuckle Jr.
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    Mar 2006
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    detonation is usually caused by excessive fuel burning at other times than what the motor was designed for. in 1:1 cars detonation can be cured by running a higher octane fuel(not sure if it will apply to rc) or running a colder plug.

    are you sure you are hearing detonation and not just a resonance sound from your pipe.

    a good sign you had detonation in a larger engine is a snaped rod or a hole through the piston
    I tried being reasonable, I didn't like it.

  3. #3
    Registered User OneBigMan647's Avatar
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    May 2002
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    Calabasas, CA
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    5,579
    Like cuda tmaxx said, you are most likely running too hot of a plug for your weather conditions, or your running on the lean side. What temps are you running at? Usually if an engine is detonating it is also overheating.

  4. #4
    RC Champion
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    Quote Originally Posted by cuda_tmaxx
    detonation is usually caused by excessive fuel burning at other times than what the motor was designed for. in 1:1 cars detonation can be cured by running a higher octane fuel(not sure if it will apply to rc) or running a colder plug.

    are you sure you are hearing detonation and not just a resonance sound from your pipe.

    a good sign you had detonation in a larger engine is a snaped rod or a hole through the piston
    In a 2-stroke RC, detonation is basically due to the engine firing too early (on the up-stroke). The cracking/popping noise you hear is because the cylinder if firing while the exhaust port is still open, thus making a backfire. Like the timing being off on a 1:1 car. This is caused by too much compression. Yes, the by-product is usually elevated engine temperatures. Typically a hotter plug requires less compression to fire so going to a colder plug sometimes fixes it. Running 30% in an engine designed or more appropriately pre-set to run on 20% is generally the culprit. Switching to a hotter plug when it is not needed will cause it as well. Adding more head shims usually fixes it, as it decreases the compression by increasing the volume of the chamber at full stroke. You have to experiment with the head shimming to get it right. Adding too much will actually make the motor lose power. In older engines that are losing compression due to wear on the piston/sleeve, you can regain some performance sometimes by going up on the nitro%. Often times, a detonating engine will burn out glow plug elements frequently. If the platinum element falls out and wedges between the exhaust of intake port and the piston, then it will usually snap a rod or piston.

    Hope this was good info for you.
    Last edited by terry; 04-19-2006 at 09:15 AM.
    -Terry
    "The best part of wakin' up....is Nitro" i

  5. #5
    RC Racer
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    Dec 2004
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    127
    it did over heat last night....it hasnt before though. I live in Florida and it might have been about 75-79 degrees last night. I had it dialed in by my brother who knows how to tune em better than I do.....dont get me wrong I can tune it....but when he got done with it..it was had the Hole Shot back. i noticed a huge improvement. it has the nice trail of smoke that we want to see, and all. it could be the MIP High End Pipe resonating.....it wasnt tuned for the pipe before either..but when it did overheat...i started thinking of the sound more and more and the possibility of detonation. maybe ill take it out again tonight and record a small clip and post it. BTW after it overheated it did not want to crank for several minuets....sounded like it was not getting spark.....dunno......thanks for the info.
    Tec Pro 3.3, MIP Stinger,Jaco Nitro Shoes, HPI WRX, VARAD Lighting System...... Check up cause I Will bump draft.

  6. #6
    RC Champion
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    Quote Originally Posted by Mista_Whiz
    BTW after it overheated it did not want to crank for several minuets....sounded like it was not getting spark.....dunno......thanks for the info.
    When it overheats, it's normal for it to be difficult to start. Try richening the high speed to get it started again, then lean it back out after you get it going, just don't lean it as much or you'll overheat again.
    -Terry
    "The best part of wakin' up....is Nitro" i

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